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Technology

Cryptographic Hash Functions and Data Integrity

Quick fact

A cryptographic hash function can take any input—even a whole movie—and produce a fixed-size string (like 256 bits). If you change just a single word in a book-length document, the resulting hash is completely different, making it nearly impossible to fake a valid hash for tampered data.

Why this is interesting

You’ve probably downloaded a file and seen a long string of numbers and letters called a hash. How can that little code tell you whether your file is exactly what the creator intended?